The present disclosure relates generally to pneumatically actuated valves and more specifically to filters for pneumatically actuated valves in bleed air systems.
Aircraft engine bleed air from the compressor stage of the engine is often re-routed within the aircraft for a number of uses, including internal cooling of the engine, cross-starting a second engine, ice protection purposes, pneumatic actuators, and many other uses. Typically, bleed air must be conditioned or directed to be used in another system. Thus, bleed air valve assemblies are used to direct and control bleed air before use elsewhere in the aircraft. Specifically, bleed valve assemblies use air filters to sift bleed air.
Typical bleed air assemblies, as found in the art, are bleed air systems with valve filters constructed of wire mesh or sintered metal screens. For pneumatic valves, the wire mesh or sintered metal screen is installed into a bore and constructed top hat style. In this configuration, the valve flange is spring loaded to seat and secure the filter element. This configuration has limited filtration capacity due to the restricted diameter of the configuration. Additionally, the micron rating of the filter is limited, as the valve would clog too quickly. Finally, this type of prior art filter lifts against the spring load when it does clog, which results in particles bypassing the filter element altogether.